Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 30, Problem 7E
What are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.
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Check out a sample textbook solutionStudents have asked these similar questions
A radio broadcast left Earth in 1911. How far in light years has it traveled?
If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast reached?
Assume that the fraction of these star systems that have planets is 0.50 and that, in a given planetary system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.20. How many possible planets with life could have heard this signal?
Tutorial
A radio broadcast left Earth in 1923. How far in light
years has it traveled?
If there is, on average, 1 star system per 400 cubic light
years, how many star systems has this broadcast
reached?
Assume that the fraction of these star systems that
have planets is 0.50 and that, in a given planetary
system, the average number of planets that have
orbited in the habitable zone for 4 billion years is 0.40.
How many possible planets with life could have heard
this signal?
Part 1 of 3
To figure out how many light years a signal has
traveled we need to know how long since the signal left
Earth. If the signal left in 1923, distance in light years =
time since broadcast left Earth.
d = tnow - broadcast
d = 97
97 light years
Part 2 of 3
Since the radio signal travels in all directions, it
expanded as a sphere with a radius equal to the
distance it has traveled so far. To determine the
number of star systems this signal has reached, we
need to determine the volume of that sphere.
V, =
Vb…
Tutorial
A radio broadcast left Earth in 1925. How far in light years has it traveled?
If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast
reached?
Assume that the fraction of these star systems that have planets is 0.30 and that, in a given planetary
system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.85. How
many possible planets with life could have heard this signal?
Part 1 of 3
To figure out how many light years a signal has traveled we need to know how long since the signal left Earth.
If the signal left in 1925, distance in light years = time since broadcast left Earth.
d = tnow - tbroadcast
d =
light years
Submit
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Chapter 30 Solutions
Astronomy
Ch. 30 - What is the Copernican principle? Make a list of...Ch. 30 - Where in the solar system (and beyond) have...Ch. 30 - Give a short history of the atoms that are now in...Ch. 30 - What is a biomarker? Give some possible examples...Ch. 30 - Why are Mars and Europa the top targets for the...Ch. 30 - Why is traveling between the stars (by creatures...Ch. 30 - What are the advantages to using radio waves for...Ch. 30 - What is the “cosmic haystack problem”? List as...Ch. 30 - What is a habitable zone?Ch. 30 - Why is the simultaneous detection of methane and...
Ch. 30 - What are two characteristic properties of life...Ch. 30 - What are the three requirements that scientists...Ch. 30 - Can you name five environmental conditions that,...Ch. 30 - Would a human have been possible during the first...Ch. 30 - If we do find life on Mars, what might be some...Ch. 30 - What kind of evidence do you think would convince...Ch. 30 - What are some reasons that more advanced...Ch. 30 - What are some answers to the Fermi paradox? Can...Ch. 30 - Why is there so little evidence of Earth’s...Ch. 30 - Why was the development of photosynthesis a major...Ch. 30 - Does all life on Earth require sunshine?Ch. 30 - Why is life unlikely to be found on the surface of...Ch. 30 - In this chapter, we identify these characteristic...Ch. 30 - Given that no sunlight can penetrate Europa’s ice...Ch. 30 - Why is Saturn’s moon Enceladus such an exciting...Ch. 30 - In addition to an atmosphere dominated by...Ch. 30 - How can a planet’s atmosphere affect the width of...Ch. 30 - Why are we limited to finding life on planets...Ch. 30 - Suppose astronomers discover a radio message from...Ch. 30 - The light a planet receives from the Sun (per...Ch. 30 - Think of our Milky Way Galaxy as a flat disk of...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
- Which of the following is not considered a likely solution to the question of why we are not currently aware of an extraterrestrial civilization? Group of answer choices There is no civilization because civilizations are not common. The civilization is probably undetectable to us because it makes use of technologies that do not obey the known laws of physics. There is no galactic civilization because civilizations do not leave their home worlds. There is no civilization because most civilizations destroy themselves before achieving interstellar travel. The civilization is deliberately avoiding contact with us.arrow_forwardasap pleasearrow_forwardWhich of the following is least reasonable regarding the difficulty in contacting extraterrestrial life using space flight and radio communication. Group of answer choices Space flight to the nearest star would take thousands of years with current technology. Even if another intelligent civilization is within a few hundred light-years of us, conversations would be very slow with a turnaround time of decades or even centuries. The spacecraft that NASA sent to Proxima Centauri a few years ago should be approaching its target within a decade or two, depending on solar wind conditions. Earth has been broadcasting at radio wavelengths since the 1930's, so any civilization within a radius of about 100 light-years or so could have received the broadcast by now. Without some major breakthrough, interstellar space flight is totally impractical.arrow_forward
- Which of the following seems least reasonable regarding life on Earth? Group of answer choices There is much scientific evidence suggesting that all creatures living on Earth today appear to have evolved from a common ancestor. Louis Pasteur discredited the concept of spontaneous generation by demonstrating that even bacteria and other microorganisms arise from parents resembling themselves. There is ample physical evidence that the earliest life forms on Earth were multicellular creatures, perhaps resembling some of our primitive fish. When the earth formed some 4.6 billion years ago, it was a lifeless, inhospitable place. Before the mid-17th century, most people believed that God had created humankind and other higher organisms and that insects, frogs, and other small creatures could arise spontaneously in mud or decaying matter About billion years into its development, the Earth it was teeming with organisms resembling blue-green algae.arrow_forwardWhy do we think we would be able to decode a message deliberately sent to us by an alien civilization? Group of answer choices The message will probably be in video format, allowing us to watch it even without knowing the alien language. We can assume that aliens will also have 10 fingers and 10 toes and therefore that they can send a message that relies on this fact. They undoubtedly have already received our television broadcasts and would therefore be likely to send the message in English. The aliens presumably know the same laws of mathematics and physics as we do and therefore could develop a simple code based on these laws.arrow_forwardSuppose astronomers discover a radio message from a civilization whose planet orbits a star 35 lightyears away. Their message encourages us to send a radio answer, which we decide to do. Suppose our governing bodies take 2 years to decide whether and how to answer. When our answer arrives there, their governing bodies also take two of our years to frame an answer to us. How long after we get their first message can we hope to get their reply to ours? (A question for further thinking: Once communication gets going, should we continue to wait for a reply before we send the next message?)arrow_forward
- Calculate the numb of communicative civilizations per galaxy using your n estimates of the factors in Table 20-1.arrow_forwardMars and Europa are two Solar System bodies that are considered possible habitats for Earth-like life. Why?arrow_forwardWhat is the difference between chemical evolution and biological evolution?arrow_forward
- What are some reasons that more advanced civilizations might want to send out messages to other star systems?arrow_forwardThe Drake equation In 1961 astronomer Frank Drakedeveloped an equation to try to estimate the number ofextraterrestrial civilizations in our galaxy that might be able to communicate with us via radio transmissions. Nowlargely accepted by the scientific community, the Drakeequation has helped spur efforts by radio astronomers tosearch for extraterrestrial intelligence. Here is the equation: NC = N # fp # ne # fl# fi# fc # fLOK, it looks a little messy, but here’s what it means:So, how many ETs are out there? That depends; valueschosen for the many factors in the equation depend onever-evolving scientific knowledge and one’s personalguesses. But now, some questions.a) What quantity is calculated by the first product, N # fp?b) What quantity is calculated by the product, N # fp # ne # fl?c) What probability is calculated by the product fl# fi?d) Which of the factors in the formula are conditionalprobabilities? Restate each in a way that makes thecondition clear.arrow_forwardPut in order the organization levels for life: Organs→ - Organisms Populations :: Tissues :: Ecosystems : Organ systems : Cells : Communities 1 2 3 4 5 6 7 Support | Schoology Blog | PRIVACY POLIarrow_forward
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